Sahara is unforgettable. It is a hot desert stretching over the territories of eleven states and once you see it you want to come back over and over again. It is on Sahara where the night comes not preceded by dusk and the far horizon disappears in overwhelming darkness. Sahara consists of several deserts. The Fayum desert, South-East of Cairo is one of the most interesting places. This often-called “Gate of Western Desert” keeps many remarkable views and until recently unknown facts from history. It was here where 40 million years ago the shallow Tethys Sea existed, which when it dried out left skeletons of prehistoric whales, tortoises and other sea creatures. The bottom of this prehistoric sea is now a part of the Egyptian desert in which the wind uncovers more and more treasures and mysteries from the far past of the life on Earth. Until not long ago it was believed that the only waterway was the Nile which allowed for African products to be moved to the costs of the Mediterranean Sea. Yet the newest discoveries show that ancient Egyptians were also using other wide rivers which were flowing through the present territory covered by Sahara. Research on climate change suggests also that this part of Africa could have been humidified by rich rainfall brought over by the monsoons from the Indian Ocean. The satellite photos of Sahara seem to affirm the thesis that before our times there was a gigantic water system present in the desert. The length of some prehistoric rivers was even over 800 km and their width – over 5 km. A team of Geo-chemists from University of Bristol decided to check if those prehistoric canals were once rivers. On the outlines of the canals they found the remains of freshwater snails and compared them to the similar species from the Mediterranean area. Such snails were probably transported by the currents of the rivers which had their origins in the Tibesti mountain range which is located in the very centre of the desert. The researchers claim that the rivers flowing from the Sahara to the Mediterranean Sea through the territories of today’s Libya could have been the main transport arteries of prehistoric people. Sahara has more secrets. Apart from the ancient rivers and the Egyptian Thetis Sea there were similar water masses discovered in the regions of present Chad, Sudan and Libya. The knowledge of the outline of the past coasts is explained by some paleo-biological finds, such as fossilised remains of fish. Interesting photographs were delivered by the international Shuttle Radar Topography Mission (SRTM), in which various organisations took part, including e.g. NASA. The objective of the mission was to collect data (from the Endeavour space shuttle) for numerical assessment of territories from various parts of Earth. This was the first mission which delivered detailed and homogeneous data for almost 80% of the land surface. During this mission the radar identified an area in North-West Sudan where 10 thousand years ago there was a lake as big that it would cover the present island of Sardinia. Eman Ghoneim from Boston University analysed the radar-made photos and noticed a dark line, approximately 250 long and 1 km wide which was very apparent on the light bedrock. Such a line is typical for layers of gravel and sand which sediment on the lake banks. The size of the lake was estimated by analysing the lay of the land. Ghoneim also identified eight tributaries in which the water flew from the nearby hills. Three of the tributaries were once sizeable rivers. This discovery allows explaining how a giant under-surface water reservoir came to existence in this region of Sahara. We admire the Mediterranean Sea when we’re walking at its shore and we do not wonder if one day it too might be covered with sand. Yet what is worth thinking about, especially when a sand storm is at its wildest, covering sea-side countries with tonnes of dust from Israel and Lebanon to Turkey and Cyprus, is that thousands of years ago under the Sahara desert there were gigantic lakes which created the beautiful Saharan sea.